1. Field of the Invention
This invention relates to a silicone rubber composition which has high plasticity in a base compound form, is suitable as extrusion molding material, and can be molded and cured into products having low hardness.
2. Prior Art
Silicone rubbers which are cured products of silicone rubber compositions are improved in heat resistance, weather resistance, durability, releasability and electrical properties and formable or moldable to any desired shape. They have found a wide variety of uses as building materials, electric and electronic parts, automobile parts and business machine parts. For automatic low-cost manufacture of such parts in a large scale, a continuous extrusion molding/heat curing process of extruding a silicone rubber composition through an extruder and continuously passing the extrudate through a hot air oven for heat curing is currently widely accepted.
There is a great demand for silicone rubber compositions for extrusion molding. Silicone rubber compositions with low loading of filler and curing into low hardness (JIS A scale hardness 40 or lower) silicone rubbers having excellent flexibility and rubber elasticity are now on the verge of industrial use. These silicone rubber compositions, however, have a problem associated with low loading of filler that rubber compound in uncured state is low in plasticity and difficult to work during extrusion molding. This problem must be solved for low cost manufacture.